If we do not render in HDR, we do light calculation with gamma 2.2 colors. To avoid this, we subtract the amount of light at the maximum distance ( dmax), the corrected formula is: If the simply cut the light at a distance, we might see the cut-off point. Ventuz light-sources define a maximum radius. Doubling the distance will quarter the light intensity. In reality, light intensity decreases with the square of the distance: I = I 0 * 1 / d 2. This is especially useful to adjust HDR lights. So a gain of 3 will increase the intensity by a factor of 8. Gain 0 will not change the light, every positive step will double the intensity of the light and every negative step will half it. With the other models, light sources will scale correctly with the world as long as the scaling is uniform in x, y and z.Įvery light source now has a gain property. With legacy falloff, light-sources do not scale with the world.When changing the falloff model (by changing the engine mode), all lights need to be adjusted for the new model.You can skip the math, but remember the following: Below is an explanation for the formulas. We use different formulas for different engine modes. This is about how light gets darker with distance. Standard Engine vs HDR mode Light Attenuation In addition, the material of an object can have an Emissive term that simulates light coming from the object itself. To disable the default lighting set the DefaultLight to " none" in the 3D Layer Root Nodeīoth the light source and the material have a color assigned to all of these terms. This so called head light is positioned at the exact position of the camera, therefore shiny objects (with a high specular amount) can appear completely white. When there is no light source node in the scene, Ventuz uses an internal default light source. Note that this will only be visible on objects that have a Material defining a specularity. Specular: Simulates the bright highlight that occurs where the reflection of the light source is visible in the surface.This gives an object its characteristic shape, brighter towards the light source and darker on the back side. Diffuse: Varies the brightness of the surface based on the light direction and the surface normal.It simulates the ambient light that exists in the background and from bouncing off other surfaces and is usually rather weak. Ambient: This term is independent of the light source and the viewer position.For each light source, a number of terms is calculated: The final color of a pixel in a triangle is dependent on the shape of the objects surface, the characteristics of the light sources, the Material applied to the object as well as the Engine-Settings in the Layer Root of the 3D Layer. It is therefore often called direct lighting opposed to global lighting as used by raytracing software.Ī triangle can be lit by one or multiple light sources. There are no global effects like one object casting a shadow onto another or light bouncing of one surface and lighting another. Lighting in Realtime Rendering is a very efficient approximation of real life lighting.
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